incubator-cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Schubert Zhang <zson...@gmail.com>
Subject Re: Regarding Cassandra Scalability
Date Thu, 29 Apr 2010 08:29:53 GMT
Yes, it is ture.
Current cassandra has many limitations or bad implementations, especially on
storage level.

In my opinion, these limitations or bad implementations are just
implementation, not the original intention of design.

And I also want to give a suggestion/advice to the project leaders, we
currently should avoid introducing too many useless/unnecessary, and forcus
on fixing bugs/re-implement some core modules.


On Sun, Apr 18, 2010 at 9:00 PM, Mason Hale <mason@onespot.com> wrote:

>
>
> On Sun, Apr 18, 2010 at 7:41 AM, Gary Dusbabek <gdusbabek@gmail.com>wrote:
>
>> On Sat, Apr 17, 2010 at 10:50, dir dir <sikerasakti@gmail.com> wrote:
>> >
>> > What problems can’t it solve?
>> >
>> > No flexible indices
>> > No querying on non PK values
>> > Not good for binary data (>64mb) unless you chunck
>> > Row contents must fit in available memory
>> >
>> > Gary Dusbabek say: Row contents must fit in available memory. Honestly I
>> do
>> > not understand
>> > the meaning from that statement. Thank you.
>> >
>> > Dir.
>> >
>>
>> The main reason is that the compaction operation (removing deleted
>> values) currently requires that an entire row be read into memory.
>>
>> Gary Dusbabek
>>
>
>
> This is a statement I wish I had run across sooner. Our first
> implementation (which we're changing now) included some very big rows. We
> ran into trouble with compaction and during hinted hand-off operations
> (which also deals with data a full row at a time) because these rows would
> not fit into available memory.
>
> I think until there are not these lurking gotcha spots like compaction and
> hinted hand-off, where a full row must fit in memory, we should not be
> making misleading statements like "Cassandra has the advantage of a more
> advanced datamodel, allowing for a single row to contain billions of
> column/value pairs: enough to fill a machine." (from:
> http://gigaom.com/2010/03/11/digg-cassandara/ ,
> http://spyced.blogspot.com/2010/03/cassandra-in-action.html). A statement
> like that should have some caveats, otherwise it reads as an endorsement, a
> suggestion even, to build a data model with massively wide rows. In
> practice, it is not feasible to have billions of columns in a single row
> because it will lead to problems with compaction and hinted hand-off, maybe
> elsewhere.
>
> Mason
>
>
>

Mime
View raw message